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CV jointed shafts , a question


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#21 ntc

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Posted 16 February 2017 - 08:14 PM

I did look at the drums, they arent that thick enough at that point to take it and if you have original Alfins like I have on my solid axle I wouldnt be altering them. The hub flange would take it as its thicker than normal but its the ally section needs a 1/32" off it too which means separating the outer hub from it, shouldnt really need to do this.

Stuart.

Stuart

I know this is wrong but could you shim the back plate?


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Regards
Neil

#22 stuart

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Posted 16 February 2017 - 10:08 PM

Stuart

I know this is wrong but could you shim the back plate?

Unfortunately not as all the extra width is outside of the back plate so you make it worse.

Stuart.


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#23 ntc

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Posted 16 February 2017 - 10:11 PM

Then if you fit disclaimer required.


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Neil

#24 stuart

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Posted 16 February 2017 - 10:12 PM

Stuart, as the shoes are narrower than the drum do you know where they would sit on a standard set up, i.e. Central, offset to the outside or offset to the inside.
Chris

Need to do some measurements but I suspect the shoes would with the extra width now be running on the very inside of the drum.

Stuart.


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#25 stuart

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Posted 16 February 2017 - 10:16 PM

Then if you fit disclaimer required.

I havent fitted this set yet, the issue came to light from one of Chris`s friends assembling his 6 with them, put it all together and wondered why the drum wouldnt sit right, we have been investigating since, his came from an outside source but turns out supplied by the same and then re-sold on.General answer from them seems to be the usual

Stuart.


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#26 TriumphV8

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Posted 17 February 2017 - 07:58 AM

As we are talkink about hints besides my idea milling the bearing housing

or make a new housing from steel it might be possible to machine the hub

at another position.

 

I do not know if there is enough material, but worth a look at:

Inside where the big bearing sits the hub has a flange where the bearing is bolted to.

this flange can be cut 1,5mm to allow the bearing to slide more,

The closest point might be the hole from opposite side to allow the centre nut to be fixed.

if there still is a convenient amoint of material remaining, so why not?

 

Eventually the end of the tube area has to be cut also this 1,5mm

that the cv-joint still spanns the bearing together.


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Cheers

Andreas


#27 RogerH

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Posted 17 February 2017 - 08:21 AM

Hi Stuart,

                not sure what would need machining to fit or why but be careful.

A couple of years ago one of the main TR garages (I'm sure it was Revington) had to sort out a CV shaft (not one of theirs)  that had burst through the hub - shaft longer than space available.

 

The kit (or the query) should be sent back to the supplier/manufacturer for their comment.

 

Roger


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#28 TriumphV8

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Posted 17 February 2017 - 09:27 AM

Hi Roger, I would expect that that shaft was too short, not to long.

 

We are talking about few milimetres to travel in length totally and even in

very, very few millimetres in difference what diff and hub flange distances differ.

Reasons can be weldings on the frame or strange setup with the shims.

 

If too long this will let the axle press outside when wheels are close to lower bumpstop.

All in all mostly a very small distance that will be accepted in the rubber bushings

maybe with strange driving behaviour but not with something to brake.

This misalignment is easy to detect when the axle is fitted.

 

My bet would be that axle was to short what is not noticed under normal driving conditions.

When driving over an obstacle the wheel can be pushed to the upper bumpstop and the

full way to travel of the cv-shaft is requiered.

 

If that is not enough the toothed end of the shaft is pushed out of the inner part of the cv-joint.

It is secured with a ring offering limited resistance against separation for inspection or renewing.

 

This pushed out shaft will have turned the inner part of the cv-joint, prohibiting that the shaft

can slide back where ist belongs. Than the wheels comes downward putting force on the shaft

until something brakes because the shaft now is much longer due to the mistake in the toothed end.

 

All that trouble started with ignoring the fitting instructions


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Cheers

Andreas


#29 stuart

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Posted 17 February 2017 - 09:32 AM

Hi Roger, I would expect that that shaft was too short, not to long.

 

We are talking about few milimetres to travel in length totally and even in

very, very few millimetres in difference what diff and hub flange distances differ.

Reasons can be weldings on the frame or strange setup with the shims.

 

If too long this will let the axle press outside when wheels are close to lower bumpstop.

All in all mostly a very small distance that will be accepted in the rubber bushings

maybe with strange driving behaviour but not with something to brake.

This misalignment is easy to detect when the axle is fitted.

 

My bet would be that axle was to short what is not noticed under normal driving conditions.

When driving over an obstacle the wheel can be pushed to the upper bumpstop and the

full way to travel of the cv-shaft is requiered.

 

If that is not enough the toothed end of the shaft is pushed out of the inner part of the cv-joint.

It is secured with a ring offering limited resistance against separation for inspection or renewing.

 

This pushed out shaft will have turned the inner part of the cv-joint, prohibiting that the shaft

can slide back where ist belongs. Than the wheels comes downward putting force on the shaft

until something brakes because the shaft now is much longer due to the mistake in the toothed end.

 

All that trouble started with ignoring the fitting instructions

No as Roger said shaft too long.

Stuart.


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#30 potts4a

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Posted 17 February 2017 - 02:02 PM

Hi Chris,
                you can get the same effect if you fit longer rear springs in order to increase ground clearance.
 
There is not a lot of leeway around the drive shafts.
 
Roger


It was mentioned to me that the acceptable dimensions would not be exceeded with a standard car fitted with lever arm shocks. I guess once a car is away from standard the onus is on the owner to ensure additional items fitted are suitable for the application at the minimum by checking with the supplier.
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#31 potts4a

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Posted 17 February 2017 - 02:12 PM

Need to do some measurements but I suspect the shoes would with the extra width now be running on the very inside of the drum.
Stuart.


Stuart, as the back plate goes behind the hub flange then the brake shoes must be in the correct position and therefore can I ask does the whole hub stick out further or is it just the wheel flange which is thicker which would hold the drum away from the shoes making them run closer to the outer ( open ) edge.
Chris
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#32 stuart

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Posted 17 February 2017 - 02:18 PM

Stuart, as the back plate goes behind the hub flange then the brake shoes must be in the correct position and therefore can I ask does the whole hub stick out further or is it just the wheel flange which is thicker which would hold the drum away from the shoes making them run closer to the outer ( open ) edge.
Chris

As I said earlier the hub is 1/32" thicker and the flange is 1/32" thicker too thus putting the drum further out. The backplate is still in its original position.

Stuart.


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#33 TriumphV8

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Posted 17 February 2017 - 02:28 PM

It was mentioned to me that the acceptable dimensions would not be exceeded with a standard car fitted with lever arm shocks. I guess once a car is away from standard the onus is on the owner to ensure additional items fitted are suitable for the application at the minimum by checking with the supplier.

 

Yes, as the movement of the shifting element in the cv-joint is not endless

the shaft length must fit to suit.

 

I think its a normal process when buying trousers to look if they fit.

If not they have to be shortened or lengthened.

Even the crank gets this procedure or the shafts in the gearbox!

 

That easy procedure should be accepted for our cars especially when there

is a leaflet with a detailed instruction and recommendation how to proceed

coming with the shafts and everybody knows that the are shims at the rear axle

that change required shaft length.

I wonder how many complains I found related to that simple problem.

-Just as much as referring to correct travel way of rear telescopic dampers-

Measuring seems to be a myth.........


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Cheers

Andreas


#34 jean

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Posted 17 February 2017 - 02:32 PM

I measured the original hub against the CDD hub and to avoid any confusion here is what I measured

 

                                                                                                                     Attached File  IMG_7990.JPG   99.38KB   1 downloads

 

Without any doubt the CDD hub will position the drum further away from the shoes and the brake plate, but depending on the drum it might still be in limits 


Edited by jean, 17 February 2017 - 02:35 PM.

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IMG_1883_1.jpg


#35 potts4a

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Posted 17 February 2017 - 03:30 PM

So, two different items under discussion here,
1.
Thickness of wheel flange and hub having a slight affect on postion of brake drum over shoes.

2. Length of driveshaft and effect of excessive up/Down movement of swinging arm on durability of CV shaft assy.
Item 1. Could impact on durability/ life of brake shoes if drum has wear ridges and is not smoothe.

Item 2. In extreeme circumstances where the movement of the swinging arm exceeds the recommended dimensions the driveshaft could fail.

With ref to item 2 the CDD recomended max drop from the underside of the wheelarch to the centre of the axle is 440mm.
Unfortunatly the wheelarch is not a reliable place to measure from as its position relative to the axle and chassis can vary car to car with size of spacers between body and chassis. When I questioned CDD on this I was told that if you knew the body had extra spacers, for example to aid door alignment then the 440mm could be exceeded by a similar amount. Also with cars set up like mine with shorter stiffer springs and koni dampers on the 3 point fixing brackets the overall movement, up/down of the axle shaft is less than a car with standard softer springs.
Even with shorter stiffer springs like I have the lower position of the swinging arm is determined by the extended length of the tele shock when fitted. It is therefore important that shocks and brackets are bought as a kit for a TR and if the shocks are replaced at a lated date then they need to have the same operating dimensions.
Chris

Edited by potts4a, 17 February 2017 - 03:33 PM.

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#36 ntc

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Posted 17 February 2017 - 03:36 PM

Tis why I never fitted them,I would stick with the cossie ones.These are also good http://www.vessey-cl...tm#.WKccl0-mljo

Attached Files


Edited by ntc, 17 February 2017 - 03:55 PM.

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Regards
Neil

#37 jean

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Posted 17 February 2017 - 05:04 PM

Yes Chris, the initial subject Stuart mentioned were the problems with the hub dimentions in relation to the brake drum, as least it was what I understood.

The driveshafts itself is in fact another subject to be watched, and you are right about the swing of the shaft, a critical item.

 

A few weeks a go I looked at a site that showed how to measure the travel in the cv joints from full compression to full extension.

This in fact is what limits the travel of the trailing arm.The upper bump stop should be no problem, but with tele.shocks the lower side might cause problems

For best results you will have to remove the springs and unbolt the tele.shocks, With the shaft bolted up to the diff and the hub left off you will be able to mesure the full travel

The position of the hub in relation to the joint has to be measured in the most upper and lowest position of the trailing arm.  

 

It's not rocket science, but it has to be done with care to avoid wrecking the joints at a later stage. 

  


Edited by jean, 17 February 2017 - 07:01 PM.

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IMG_1883_1.jpg


#38 Motorsport Mickey

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Posted 17 February 2017 - 06:06 PM

Jean,

 

Unbolting the shock absorbers and removing the springs will give the very worst "droop" conditions possible of the rear trailing arms as they extend the CV driveshafts up to and possibly beyond the actual driveshaft operational range. There has been a least a couple of owners on Stags and TRs where the car has been suspended on a lift with the rear wheels left to hang free and completely unsupported without the rear shock absorbers fitted (which are the ONLY restraints against overextension) and the CV driveshafts have been damaged. 

I would not carry out a "full droop" exercise WITHOUT the shock absorbers being fitted, they act like the bump stops do in the upward direction by compelling the driveshafts to work ONLY in the range they are engineered to. I'm not sure if by removing the restraining shock absorber and drooping the trailing arms that it may cause the driveshaft joints (large balls in some I've seen) to become unrestrained and damaged if they are not replaced correctly (how would you know with them assembled ?). 

Unless the driveshaft supplier gives an exact method for driveshaft full extension testing and measurement I would be wary of applying the test as you have just outlined with a driveshaft connected at both ends.

 

If the vehicle is in use and the trailing arms need to go onto full unrestrained droop in the garage (for rear spring removal etc) then I would unbolt the driveshaft from the flange at the diff and "ease" the driveshaft flange away from it by about 50mm which would allow the driveshaft to be pulled down by wheel hub without overextending it where you can carry out your work safely on spring removal or whatever before connecting the driveshaft back up.

 

Mick Richards   


Edited by Motorsport Mickey, 17 February 2017 - 06:26 PM.

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#39 jean

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Posted 17 February 2017 - 07:00 PM

Very correct Mick, Unfortunately my wife was waiting with dinner and it would not have been wise to delay her.... :blink:

 

If not I could have said that the drop of the trailing arm has to be done   WITHOUT   the hub being fitted.

In the middle and at both ends of the travel the hub has to be inserted into the splines up to the back plate.

With the nut loosely fitted you have to measure the threat sticking out of the hub.

The number measured will show you how far the up and down movement is in acceptable limits. The number is indicated, but I don't remember

Before fitting the shafts I was looking how to fit eventually additional bump stops to limit the downwards travel, I have Konis on my car and don't know how much load they can take. 

 

You are right and my apologies for not having finished my text.. :(


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#40 Motorsport Mickey

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Posted 17 February 2017 - 07:13 PM

No problem Jean, I often "transgress" with my wife and I still bear the "scars" :o if late for dinner, lol.

 

Mick Richards

 


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